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Position Sensitive Detectors Project

Quick links to subjects of interest:

• Germanium detector development (images) 
• device characterization
• germanium packaging
• germanium and silicon device development
• laboratory
• Compton telescope
• 3-Compton technique
• NRL Advanced Compton Telescope
• ATHENA
• Gamma Ray Tracking Detectors
  
• Hard X-ray Telescope (HXT)
• Polarization
• Monte Carlo modeling 
• PSPMT detector testing and CMOS readout
• CMOS electronics development
• strip detector readout electronics
• Cross section reference material
  

In nuclear astrophysics, it is generally agreed there is a need for an instrument with one to two orders of magnitude higher sensitivity than is now possible with instruments such as OSSE and COMPTEL on NASA's Compton Gamma Ray Observatory .  With this sensitivity, nuclear lines -- the direct signature from the formation of matter (nucleosynthesis) -- will be observed from distant supernovae in galaxies out to ~100 Mpc from Earth.  Many other scientific objectives require similar improvements, such as the measurements of the cut-off in spectra from active galactic nuclei, black hole accretion disks, and pulsars.  We have been studying a promising new instrument concept that exploits the Compton scattering process to achieve these necessary sensitivity to meet these scientific objectives. 

We are working on a variety of instrument concepts and detector technologies in order to realize these and many other goals.  Our detector development work includes many detector materials and configurations, ranging from semiconducting detectors to scintillators. 

• Germanium strip detectors combine both the excellent energy resolution typical of germanium detectors and the fine spatial resolution possible in a strip detector. They are applicable in a variety of applications where high sensitivity, imaging, and spectroscopy are important.  Applications include coded aperture imaging, Compton telescope , hard X-ray focal plane behind a grazing incidence mirror, Doppler measurements, and gamma-ray polarimetry . 
• Germanium pixel detectors are being developed in collaboration with other institutions.  The lower capacitance of the small pixels compared with that of a strip detector promises to provide improvements in energy resolution for a large area imaging readout. 
• Silicon strip detectors for hard X-ray imaging.  The silicon detector is similar to the germanium detector in many ways.  The primary differences are that it has less stopping power, but it can be operated at warmer temperatures.
• Position sensitive photomultiplier tubes ( PSPMT ) to determine the position of interactions in a scintillator.  Scintillators coupled to PSPMTs form the detector array in the proposed BLAST mission, designed to localize gamma ray burst locations with arc second accuracy.